A centrifuge, quite simply, operates by spinning a rotor containing a sample at a certain speed for a certain amount of time at a given temperature. Ascertaining the run program, namely speed, time and temperature, appropriate for the sample, however, is not so simple. Complicating the matter is a variety of factors such as density of the specimen, the gradient used, the type of separation desired, the sample volume, and so on. Moreover, the availability of numerous centrifuge systems requires the additional consideration of the capabilities of the particular centrifuge device, the type of rotor and the tube and adapters being used.
Present centrifuge systems require the user to determine the run parameters, or the run program, for a particular centrifugation experiment of a sample of interest. Typically, this involves conducting a tedious and time consuming search of the literature to find a protocol for the same experimental conditions. Many thousands of protocols have been defined for a multitude of centrifugation experiments, and many more continue to be developed. Oftentimes, the user will find a centrifugation protocol that is similar to the desired experiment but otherwise inadequate for the specific task. A series of trial centrifugation runs must then be performed to obtain protocol parameters that are appropriate for the desired experiment.
Advances in centrifuge systems typically have been directed toward improving the performance of the hardware, such as: providing rotor designs which can withstand the extreme stresses of high speed centrifugation; sophisticated temperature controlled rotor chambers; and lightweight tube and adapter designs, allowing higher centrifugation speeds. Other advances are directed to minimizing the centrifugation time. For example, U.S. Pat. Nos. 4,941,868 and 5,171,206, which are assigned to the assignee of the present invention, disclose methods for minimizing centrifugation time. The '868 patent uses a dynamic simulation of gradient salt sedimentation to predict the elapsed time at which the precipitation threshold is reached for various speed settings. Knowledge of these predicted elapsed times allows the centrifuge to be operated at maximum speed thus decreasing centrifugation time, while at the same time avoiding precipitation of the gradient salt. The '206 patent decreases centrifugation time by continuously adjusting the rotor speed to maintain a maximum rotor speed. In U.S. Pat. No. 5,287,265 assigned to E.I. duPont de Nemours, an input device facilitates the entering of rotor speeds settings, addressing the inconvenience caused by the fact that rotor speed settings can range from two to six digits.
Despite these advances in centrifuge systems, it is still the task of the researcher to search for the correct protocol and to determine the proper run program in order to perform the actual experiments. A centrifuge, however, is one of number of tools which the researcher uses in solving the problem at hand, and so should be easy to use. Computing the operational run program for a centrifuge run and adjusting the centrifuge for the actual experiment generally do not relate to the problem being addressed. The researcher is burdened with unnecessary detail which tends to be distracting and therefore inefficient.
What is needed is a system and a method of operating which allows the researcher to interact with the centrifugation protocol from the point of view of the sample on which the centrifugation is to be performed, and not with respect to specific speed settings and rotor selections. A system and method of operating also is needed to facilitate the management both of the many known centrifugation protocols and of newly developed protocols.